Luis rode his bike for $3$ miles on each of the past $9$ days. How many miles did Luis ride his bike altogether?
The total number of miles biked is the product of the number of miles biked each day and the number of days that Luis went biking. The product is $3\text{ miles per day} \times 9\text{ days}$ $3\text{ miles per day} \times 9\text{ days}= 27\text{ miles}$ Luis biked a total of $27$ miles.